1. Field of the Invention
The present invention relates to a camera lens assembly, and more particularly to an optical image stabilizer for correcting distorted images arising from hand trembling during photographing of an object.
2. Description of the Related Art
With the recent development of a technology for miniaturizing and downsizing a digital camera, it has been possible to integrate a camera function to a mobile communication terminal. Therefore, the usage of a mobile communication terminal equipped with an optical lens and a camera device has been widely spread.
Due to mobility, images are distorted due to vibration or hand trembling arising from the human body. Thus, as photographing during movement increases, it is necessary to correct vibration such as hand trembling in order to obtain clear images.
The current image stabilization technology may be classified into an Electronic Image Stabilization (EIS), e.g. Digital Image Stabilization (DIS) and an Optical Image Stabilization (OIS). According to electronic image stabilization method, hand trembling is detected from the photographed images, then stored image data in a camera device or a memory are corrected. In other words, a camera device receives distorted images intact and adjusts positions, colors, etc., of the distorted images by electronic methods or programs, thereby minimizing images distortion.
Such an electronic image stabilization is advantageous in that it does not need a separate mechanic and physical construction, and has a low price and low structural restriction. Further, it can be easily employed. However, since the electronic image stabilization corrects distorted images using a software, it needs a separate memory or a camera device with high performance. Also, since it takes much time to correct distorted images, photographing speed may become slow. Furthermore, since there is a limitation in removing afterimages using a software, the correction rate may deteriorate.
Meanwhile, in the OIS method, the hand trembling of a user is detected, and the position of an optical lens or a camera device is altered, so that it is possible to alter images of an object formed on the camera device to compensate for the trembling.
As an OIS needs a separate driving apparatus, manufacturing cost increases and an installation space must be provided. However, since the OIS can remove afterimages by settling images with no distortion on a camera device, it is possible to maintain a correction rate greater than 90%. Hence, the OIS can photograph a more clear image as compared with the electronic image stabilization. Accordingly, in a photographing apparatus requiring high resolution, the OIS is preferable to the electronic image stabilization.
A technology for correcting hand trembling, etc., by moving an optical lens may be used in a digital camera if there were enough space to include a driving unit for driving the optical lens. However, due to limited available space in a small digital camera or a mobile communication terminal, this solution is not desirable. Therefore, research into a technology for correcting hand trembling, etc., by merely moving a camera device has been actively conducted.
As illustrated in FIG. 1, a conventional camera device 10 has a construction in which an image sensor 21 mounted on a predetermined frame 11 transmits photographed image information while communicating with a main circuit board through a flexible printed circuit 41. The flexible printed circuit 41 has a construction in which a copper plated wire 44 pattern is formed on a flexible base 43 for maintaining the board shape, and a cover layer 45 is formed so as to prevent a disconnection of the copper plated wire 44 and insulate the copper plated wire 44.
However, in constructing an optical image stabilizer for a camera lens assembly, a flexible printed circuit connected to a camera device may lower the correction rate for hand trembling. That is, a camera device moves with both an oscillation frequency within several tens of Hz and fine amplitude by the optical image stabilizer. Therefore, the camera device needs a larger driving force due to the load of a flexible printed circuit. Further, since the load of the flexible printed circuit does not always operate constantly, it may deteriorate the correction rate. The deterioration of the correction rate becomes more severe when a camera device moves in a direction vertical to a longitudinal direction of a flexible printed circuit during an image correction. Further, increase in a driving force required for correction of hand trembling, etc., causes increase of power consumption, thereby shortening the lifespan of a rechargeable battery of a photographing apparatus such as a wireless terminal equipped with a digital camera or a camera lens assembly. Moreover, in the case of using a high performance of camera device with a high number of pixels, an increased number of plated wires are required and the width of a flexible printed circuit increases. Therefore, the load of such a flexible printed circuit may cause the correction rate to be further deteriorated.